public 	Integer push(Integer item) throws FullStackException{
    	if(item == null)
    		return null ;
    	if(top == capacity)
    		throw new FullStackException() ;
    	 arrStack[top++] = item ;
    	 return item ;
    }
	public Integer pop() throws EmptyStackException{
		if(top == 0)
			throw new EmptyStackException() ;
		return arrStack[--top] ;
	}
	public Integer peek() throws EmptyStackException{
		if(top == 0)
			throw new EmptyStackException() ;
		return arrStack[top - 1] ;
	}